ETFE Membrane Research Articles

Transition Metal and Nitrogen-Doped Carbide-Derived Carbon/Carbon Nanotube Composites As Cathode Catalysts for Anion-Exchange Membrane Fuel Cells

Energy is an essential part of our lives and causes a significant impact on the environment. As the energy carrier, hydrogen could be a feasible option as it is readily producible and cost-efficient.1 In the transport sector, the proton exchange membrane fuel cells, which use hydrogen as the fuel, are already used, but have issues regarding the usage of high amount of precious metals. However, replacing acidic media with alkaline gives better possibility to use non-precious metal catalysts, especially for the cathodic oxygen reduction reaction (ORR). This suggests that anion exchange membrane fuel cells (AEMFCs) have great promise as future energy devices.2 As non-precious metal catalysts, different transition metal and carbon-based materials have shown great promise.3 Herein, a nanocarbon composite based on carbide-derived carbon/carbon nanotube (CDC/CNT) is used as a support to prepare M−N−C type catalysts. The CDC/CNT composite offers a novel structure containing both micro- and mesopores that is beneficial for the AEMFC application. The composite material is doped with nitrogen and transition metals using pyrolysis at 800 °C in inert atmosphere. As precursors, metal acetates (iron(II) and cobalt(II) acetate) and 1,10-phenantroline are employed. Three M-N-C materials are prepared, namely Fe-N-CDC/CNT, Co-N-CDC/CNT, and bimetallic CoFe-N-CDC/CNT.4 Different physico-chemical characterization methods (SEM-EDX, XPS, XRD, MP-AES, and N2 physisorption) are used to study the catalyst materials, which proved the success of doping (metal content ca. 1 wt%) as well as the feasible micro- and mesoporous structure with defects present. The RRDE method was used for electrochemical testing to study the ORR pathway and activity. In alkaline medium all three catalyst materials exhibit good electrocatalytic activity for the ORR with the peroxide yield depending on the metal additive in order Co > CoFe > Fe. The materials are applied as cathodes in the AEMFC together with ETFE membrane. The MEA with the CoFe-N-CDC/CNT cathode shows the best performance in H2/O2 AEMFC and a very good performance in H2/air AEMFC by obtaining respective peak power densities of 1.12 and 0.80 W cm–2 (Fig. 1). Additionally, the CoFe-N-CDC/CNT exhibited good stability in both AEMFCs. This shows that the M-N-CDC/CNT materials are promising cathode catalysts for the AEMFC application.4 References O. Abe, A. P. I. Popoola, E. Ajenifuja, and O. M. Popoola, Int. J. Hydrogen Energy, 44, 15072-15086 (2019).S. Gottesfeld, D. R. Dekel, M. Page, C. Bae, Y. S. Yan, P. Zelenay, and Y. S. Kim, J. Power Sources, 375, 170-184 (2018).A. Sarapuu, E. Kibena-Põldsepp, M. Borghei, and K. Tammeveski, J. Mater. Chem. A, 6, 776-804 (2018).J. Lilloja, E. Kibena-Põldsepp, A. Sarapuu, J. C. Douglin, M. Käärik, J. Kozlova, P. Paiste, A. Kikas, J. Aruväli, J. Leis, V. Sammelselg, D. R. Dekel, and K. Tammeveski, ACS Catal., 11, 1920-1931 (2021), Figure 1

Material saving and building component efficiency as main eco-design principles for membrane architecture: case - studies of ETFE enclosures

ABSTRACT Compared to the traditional materials, textile membrane and foil structural enclosures use minimal quantity of materials to cover spaces or close façades, thanks especially to their tensioning ability, by shaping themselves to the forces ways, with a few additional stiffening components. However the environmental compatibility, due to their actual fossil fuel origin, together with the thermal, optical, and acoustic performances are crucial factors to be verified during the design phase. The need of understanding their potentials and limits in terms of eco-efficiency is on the debate. Starting from these concepts, the aim of the research is to demonstrate the advantages of the Life Cycle Design strategy answering to the environmental sustainability of membrane building components.The authors found out two eco-efficiency principles for the application of membranes and foils, orienting the designers towards a more sustainable whole life spanned lightweight technology’s choice. The main advancement of this research is presented adding new ETFE membranes case studies to the initial analysis (Monticelli, Zanelli, 2016). The aim of this ex-post application of the principles on built examples is the demonstration of their validness for the designer’s need and the intention is to spread their use during the early design stage. The calculation on a wider and different use of membranes allowed to sketch benchmark reference rates. The results of the data analysis show how lightweight technologies offer a high degree of freedom in shaping geometries and forms, while only their optimized application can guarantee a sustainable and LCA effective result.

Field study of indoor environment quality in an open atrium with ETFE membrane in a healthcare facility

The hospital street is widely utilized in the modern health care facilities as a main traffic streamline to connecting all of the outpatient rooms and treatment departments for easy access. This study investigate the indoor environment quality of a typical hospital street, i.e., a high space atrium with ETFE membrane structure in the top. The investigation combines the on-site measurement and subjective survey. The results indicates that the indoor air temperature in the atrium reaches up to 32.6oC in a summer day causing thermal discomfort according to ASHRAE 55. The CO2, PM2.5, TVOC concentration in the hospital street comply with the Chinese standard for hospitals. The illumination in the corridors around the atrium is below the threshold of Chinese standard, i.e., 100 lux. Due to the vibration of the light ETFE membrane structure, the noise level in rainy days is as high as 79.5 dB which causes acoustic discomfort of occupants. This study is beneficial for the design of the hospital street design with the ETFE membrane structure.

The Effect of Water Spray Systems on Thermal and Solar Performance of an ETFE Panel for Building Envelope

ETFE membranes are generally used in architecture for large roofing and façade systems, because of their transparency and lightness compared to glass alternatives. Multilayer ETFE panels are used to improve single membrane systems performances, reducing thermal losses, by the use of an air gap between two or more ETFE foils, generally serigraphed or surface treated to reduce solar gains. Surface temperatures and global solar radiation strongly affects mean radiant temperature (MRT), and comfort perceived by a user facing a transparent envelope as well as solar gains strongly influences primary energy use for cooling in summer conditions.In the following paper an alternative dynamic solar gains mitigation strategy is presented and applied to a double layer, non-cushions, ETFE panel for façades. We measured the effectiveness of a water spray system located in the air-gap between the parallel ETFE foils and used to reduce surface temperatures and solar access depending on different summer solar radiation values and outdoor/indoor air temperature conditions. Systems alternative with different in nozzle dimension, water spray geometry and water consumption were already tested to evaluate the best compromise between solar gains reduction and water use. The results are preliminary but we noticed that a reduction up to the 10% of the total solar gains could be achieved as well as a reduction of 10°C of surface temperature. Comfort evaluation for a standard indoor space were already done.

Applied Research of ETFE Membrane Gas Pillow Structure in Modern Stadiums

The ETFE membrane structure is a new type of building materials, compared to traditional wall material, which has a more significant advantages and modern forms of spatial structure and it will be trend to replace traditional materials. This study, using literature data, based on analysis of the ETFE cushions structure graphics and ETFE materials characteristics, taking the Beijing Water Cube Aquatics Centre as main case, focuses on the ETFE membrane structure of the basic information and this material in the field of sports building design principles and installation methods in order to promote the application of the ETFE membrane material in the field of sports building.

Cation-Exchange Membranes Prepared by Pre-Irradiation Grafting of Acrylic Acid and Sodium Styrene Sulfonate onto ETFE Membranes

Poly (ethylene-co-tetrafluoroethylene) (ETFE) membranes were irradiated by electron beams and then acrylic acid (AA) and sodium styrene sulfonate (SSS) were grafted onto the membranes, in an attempt to prepare cation exchange membranes containing -COOH and -SO3Na groups. The grafting yield was found to be strongly dependent on the synthesis condition such as irradiation dose, co-monomer composition. Infrared spectroscopy of the grafted membrane confirmed the existence of sulfonate and carboxylic acid groups. The membrane resistance decreases with the increasing of grafting yield

DESIGN, CONSTRUCTION AND MAINTENANCE OF GREENHOUSE STRUCTURES

In this paper a review is given about the effects of different parts of the solar radiation and its importance for plant growth in greenhouses. Besides the most important visible part of the light (PAR), ultraviolet (UV), near infrared (NIR) and far infrared (FIR) are discussed. The strength of the greenhouse structure can be calculated following the new European Standard for Greenhouses EN 13031-1. The orientation and the roof inclination at the greenhouse have limited influence on the light transmittance. The most important material properties of greenhouse cladding materials are presented for glass, plastic sheets (PMMA and PC) and plastic films (PE, PVC and ETFE). These properties can be modified in the different materials, which leads to improvements of the materials with respect to light transmission, heat transfer, condensation behaviour, etc. Some recent results of research of greenhouse cladding materials and structures are described, like `floating greenhouses?, `closed greenhouses?, ETFE membrane, a greenhouse for tropical lowland, zigzag-shape double PC-sheet and microstructural coated glass.